CHAPTER X 
THE COLOURS OF FISHES 
The Colours of the Lower Vertebrates—General Characteristics 
of Vertebrate Coloration—Colours of Fishes, their Char¬ 
acters and Distribution in Tropical, Abyssal, and Temper¬ 
ate Forms—Coloration of Flat-fishes—The Pigments and 
Structural Colours of Fishes. 
Of Vertebrates below fishes little need be said as to 
colour or pigments. The Tunicates alone display 
any marked colouring, and are often bright and varied 
in tint. The pelagic forms are mostly transparent 
and almost colourless, and, as we have seen, they are 
often brilliantly phosphorescent. Those of sedentary 
habit, on the other hand, often show a great range 
of colour. Krukenberg describes the species of the 
genera Didemnum and Botryllus , in the neighbour¬ 
hood of Trieste, as exhibiting the following colours : 
—blue, violet, yellow, yellowish-green, orange, brown, 
and black, and observation on the shore confirms 
this impression of prevalent brightness of tint. 
Krukenberg made a few observations on the pig¬ 
ments which are of interest. The red and yellow 
colours are apparently due as usual to lipochrome 
